XIII. Researches on turacin, an animal pigment containing copper.─II

Abstract

Since the publication of my paper on Turacin, read before the Society in May, 1869, several interesting facts have come to light in reference to the Touracos, and to the occurrence of copper in the animal kingdom. Before giving the results of my own further researches, I would first of all mention the book on “ Angola and the River Congo by the late J. J. Monteiro. In the second volume of this work, pp. 75 to 79, will be found some curious particulars about two species of Turacus ( Corythaix ), as well as an account of Mr. H. Bassett’s experiments with turacin, to which further reference will presently be made. Mr. Monteiro describes a singular trait manifested by one of his tame plantain-eaters, a Turacus schalowi , which showed marked delight in gaily coloured dresses and pictures. Several instances are given of Touracos in captivity having moulted and then renewed their crimson plumage with all its original richness of colour. Some feathers from these birds, which Mr. Monteiro handed to me for examination, were found, by optical tests, to contain a turacin identical with that which colours them in their native countries. Yet these feathers had been produced in captivity, and after the birds had been for several years in England, where they were fed upon imported bananas and other vegetable foods. Certainly they had not had the opportunity of picking up "the grains of malachite and of other copper minerals to which, it has been suggested, they may have had access in heir African homes, and from which they might have derived the copper necessary for the formation of their cupreous pigment. Such a suggestion appears, however, of doubtful value, for the plantain-eaters are arboreal feeders; and it is unnecessary, since copper is now known to be very widely distributed in plants, and I have shown it to be present in decided traces in bananas, the chief food of many species of Touraco. In 1881 Dr. M. Giunti published a paper entitled “Ricerche sulla Diffusione del Ramo nel Regno Animale.” This memoir gives a résumé of the work previously done on this subject, but also contains many new observations. Dr. Giunti found in the ash of the animals and animal products named below the following percentages of copper oxide (CuO):—